Problem with ryzen computer

[cman458]

So I recently built a new computer with a ryzen r7 1800x, with some corsair ram (2x8GB), a MSI GTX 1080 gaming Z (not x), and a MSI B350M mortar. Once I got everything halfway hooked up, enough to boot to the bios (with gpu in) and it booted to the bios, so I finished my build by connecting my ssd and HDDS and managed my cables, once I tried to boot it up, the computer turned on, but it wouldn't show anything on my monitor, and the mouse and keyboard wouldn't light up at all indicating that the computer doesn't recognize anything plugged into it, I cant remember what I did, but I did get my computer to boot to the OS once, but it never came back up. So I took my computer to best buy because I couldn't think of anything else to do. I had them test everything and the next day I am told that my gpu wouldn't fit properly into my motherboard and that the cpu was damaged. So I replaced the cpu and the computer still won't show anything on the monitor and the keyboard and mouse still won't light up. I don't know if my ram is not compatible or if I should just replace my ram and motherboard. Help and/or advise would be much appreciated.